Not Applicable.
This invention relates to clutches, and, in particular, to a locking clutch that connects two or more mechanical components together for torque and/or power transmission.
Various clutching devices are used to selectively connect mechanical components together so that they can rotate at the same angular speed about a common axis, allowing torque and power to be transmitted from one component to the other. There are two common types of clutches: (1) progressive engagement clutches, such as friction clutches or multi-disc clutches; and (2) positive engagement clutches, such as dog clutches. A friction clutch assembly usually contains two sets of friction plates mounted respectively to driving and driven parts. It relies on friction force to transmit torque and power. The friction clutch provides high performance at differential speed engagement. Frictional clutches are widely used in automotive transmissions. The construction of a friction clutch, however, is very complex, involving frictional materials and usually requiring hydraulic systems to provide and maintain adequate normal forces. Consequently, the costs associated with design and manufacture of friction clutches are high. In addition, the power losses of running the hydraulic system associated with friction clutches are high.
Positive engagement clutches, such as dog clutches, are much simpler in construction. A dog clutch typically includes a pair of jaws directed towards each other for engaging or disengaging the driving and driven parts. Dog clutches are used in hydro-mechanical transmissions and other continuously variable transmissions. They are also used in four-wheel drive vehicles for engaging the secondary driving wheels. However, the engagement is not always trouble free. There are times when the jaws of one member are not aligned up well with the grooves on the mating member. In this instance, the jaws will not engage into the grooves no matter what force is used to push the two members together.
The present invention relates to a positive clutch that connects two or more mechanical components together for torque and power transmission. The two components (i.e., the drive and driven parts) can be engaged under any angular alignment condition, thus, making engagement of the two components easier. Further, the required engagement force is small and little or no power is needed to maintain the engagement of the two components of the clutch.
Briefly stated, a locking clutch of the present invention comprises a toothed member and a slide assembly. The toothed member is connected to a drive part; and the slide assembly is connected to a driven part, or vice versa. The toothed member and the slide assembly can be brought into or out of engagement to transfer, or stop the transfer of, power and/or torque from the drive part to the driven part.
The toothed member comprises a cylindrical surface and a plurality of teeth spaced about and extending from the cylindrical surface. The slide assembly includes a body and plurality of slide members which are received in channels in the body. The slide members are movable between a retracted position and an extended position relative to the channels. A biasing element biases the slide members to their extended position.
The teeth of the toothed member are spaced apart to define a gap between the teeth. The gap has a width, at the outer ends of the teeth, at least as large as the width of the slide members to allow the slide members to be received in the gap. When the toothed member and the slide assembly are urged into engagement, at least one of the slide members is received in a tooth gap of the toothed member, thereby positionally fixing the toothed member and the slide assembly relative to each other, to enable the transfer of power and/or torque from the drive part to the driven part. The remaining slide members are urged to their retracted positions.
The number of teeth in the toothed member is not equal to (and is preferably smaller than) the number of slide members in the slide assembly. Preferably, the number of teeth is evenly divisible by the difference between the number of slide members and the number of teeth. The gap or space between adjacent teeth has a width, at the ends of the teeth, greater than the width of the slide members. Additionally, the side surfaces of the teeth can be shaped to correspond generally to the shape of the slide members.
The slide assembly can be formed such that the slide members move either axially or radially.
In the slide assembly in which the slide members move axially, the slide assembly comprises a base and a wall extending from an end surface of the base. The wall is narrower than the base, and the base and wall in combination define a shoulder where they intersect. A plurality of channels are formed in the wall and extend into the base. The channel comprises a pocket which extends into the base from the shoulder, and a groove in the wall above the pocket. A slide member (such as a roller) and a resilient member (such as a coiled spring) are received in each channel pocket. The slide member is slidable axially in the channel pocket. A stop, preferably in the form of a snap ring, extends around the slide assembly wall above the slide members. The snap ring is positioned to prevent the slide members from fully exiting the pockets to maintain the slide members in the slide assembly pockets. The spring member urges the slide member axially toward the snap ring.
In one version of the clutch with axially moving slide members, the teeth are formed on an exterior surface of the toothed member. In this instance, the slide assembly base and wall share a common outer surface. The slide assembly base and wall define a ring, and the shoulder extends radially inwardly from the inner surface of the ring. Hence, the channels (with associated pockets and grooves), and slide members are all positioned along an inner surface of the slide assembly ring.
In a second version of the clutch with axially moving slide members, the toothed member is annular in shape and has an inner surface from which the teeth extend. In this embodiment, the toothed surface is the inner surface of the toothed member. The slide assembly base and wall, in this instance, share a common inner surface (or are cylindrical in shape); the channels are formed on an exterior surface of the slide assembly wall; and the shoulder extends radially outwardly from the wall. Hence, the channels (with associated pockets and grooves), and slide members are all positioned along an outer surface of the slide assembly.
In a third version of the clutch with axially movable slide members, the toothed member is in the shape of a ring and has both an inner surface and an outer surface, with teeth extending from both the inner and outer surfaces. The clutch includes an outer slide assembly which is engageable with the outer teeth and an inner slide assembly which is engageable with the inner teeth. The outer slide assembly is identical to the slide assembly described above in the first version, and the inner slide assembly is identical to the slide assembly described above in the second version. In this third version, a single drive part can drive two driven parts, either individually or simultaneously. Alternatively, two different drive parts can individually drive a single driven part.
In the second embodiment of the clutch, the slide members move radially, rather than axially. This clutch also includes a toothed member and a slide assembly which are moveable between a first position in which the two members are engaged with each other to transmit power and/or torque and a second position in which they are disengaged from each other to prevent the transmission of power and/or torque.
The toothed member comprises a surface which is generally circular in plan and a plurality of teeth extending from the surface. The slide assembly member comprises a body having a circumferential surface which is generally circular in plan and a has plurality of axially extending channels formed in the circumferential surface. The channels have a radial opening and a stop. A slide member and a resilient member are received in each of the channels. The slide member includes a tooth engaging portion which is sized and shaped to extend through the radial opening of the channel and a shoulder which engages the stop. The slide member is movable between an extended position in which the tooth engaging portion extends through the opening and a retracted position. The resilient member biases the slide member to its extended position.
In the illustrative embodiment, the channels extend between the front and back surfaces of the slide assembly body to be opened at their axial ends. To close the axial ends of the channels, the slide assembly includes a front cover plate and a back cover plate. The cover plates are sized to close the open axial ends of the channels and have axial extending lips which extend over a portion of the radial opening of the channel such that the radial opening has a length shorter than the channel. The lips of the cover plate form the stops which retain the slide member in the channel.
The slide member itself has a base portion having a length greater than the length of the radial opening. The tooth engaging portion of the slide member is shorter than the base and sized to extend through the radial opening. The tooth engaging portion and the base define a shoulder which engages the stop.
As with the first embodiment having axial movable slide members, when the slide assembly and the toothed member of this embodiment are engaged, at least one of the slide members will be received in a gap between the teeth of the toothed member. The slide members that are not received in a tooth gap, will be urged by the teeth of the toothed member to their retracted positions.
Like the clutch with axial movable slide members, the clutch with radial movable slide members can be constructed such that the teeth of the toothed member are on inner or outer surfaces of the toothed member. In such cases, the radial movable slide members will extend from circumferential outer or inner surfaces, respectively, of the body of the slide assembly. Additionally, the clutch tooth member can be annular in shape and have both inner and outer teeth, to be matable with an inner and an outer slide assembly.